Cattle Nutrition
Digestive System
Cattle are what we call ruminants and have a ruminant digestive system. Ruminants have a four compartment stomach that includes the rumen, reticulum, omasum, and abomasum. The food then enters the small and large intestine, similar to other mammals.
Chew on That!
Cattle are known for chewing their cud. They take big bites of grass or food and store it in their rumen for the microbes to begin breaking down. When they're ready, the cow takes a break and spits up the food one bite at a time to rechew it! This process of "chewing the cud" helps break down tough plant material and allows the cows to get more nutrients.
Rumen
The rumen (on the left side of the animal) is the largest stomach compartment and consists of several sacs. It can hold 25 gallons or more of material depending on the size of the cow. Because of its size, the rumen acts as a storage or holding vat for feed.
Reticulum
The reticulum is a pouch-like structure in the forward area of the body, close to the heart. The tissues in the reticulum form a network similar to a honeycomb. A small tissue fold lies between the reticulum and rumen, but the two aren’t separate compartments. Together they’re called the rumino-reticulum. Heavy or dense feed and metal objects eaten by the cow drop into this compartment.
Omasum
The omasum is a globe-shaped structure containing leaves of tissue (like pages in a book). It absorbs water and other substances from digestive contents. Feed material (ingesta) between the leaves will be drier than ingesta found in the other compartments.
Abomasum
The abomasum is the only compartment lined with glands. These glands release hydrochloric acid and digestive enzymes, needed to breakdown feeds. The abomasum is similar to a nonruminant stomach.
Holy Cow, That's Huge!
Cattle's digestive system is huge! The 4 compartment stomach, small intestine, and large intestine can hold approximately 89 gallons of material! A person's small intestine is about 20 feet long, whereas a cows is about 150 feet long!
Ruminate on This
Calves don't have a full developed digestive system at birth. Since they will be getting their nutrition from milk there is no need for a rumen, reticulum, or omasum. Calves have a fully developed abomasum where they absorb nutrients from their mothers milk, as they grow and develop so does their digestive system! Once a calf begins to graze solid foods the three remaining compartments begin to develop and they will start to ruminate!
Learn more about a cows digestive system here: https://extension.umn.edu/dairy-nutrition/ruminant-digestive-system
Nutrients
So we have this great big digestive system, but what do we put in it? There are 5 main components to feeding any animal: Water, Energy, Protein, Vitamins, and Minerals. Of course we know where to get water from, but how do we get the other nutrients?
Energy
Energy is a nutrient that can be found in many feed stuffs for cattle. We can get the most 'energy' from carbohydrates. Carbs can be found in forages (grasses & legumes) or supplemental feedstuffs like grains (corn, oats, etc.). We can determine how much 'energy' a food has in a lab, this is often called digestible energy (DE) or total digestible nutrients (TDN).
Protein
Protein is a critical nutrient for cattle and is responsible for many bodily functions, including muscle growth. Protein is often the most expensive nutrient to feed cows because plants high in protein are more expensive or harder to grow. Plants like soybeans or alfalfa are very high in protein.
Vitamins
Cattle need six vitmains: A, B, C, D, E, & K. Some of these can be made right inside the body of the cow by the microbes in their rumen (Vitamin B & K), but the rest need to be eaten for the cow to get them. Cattle fed good quality forage rarely are lacking in vitamins but sometimes supplementation is needed if they are fed a lot of hay and little other feedstuffs.
Minerals
Cattle require at least 17 different minerals in their diets to meet their needs. The most important minerals are called "Macro-minerals" and include things like calcium, phosphorus, potassium, among others. Macro-minerals are something cows need a lot of. Micro-minerals are minerals that cows need, but not a lot of. Some examples of micro-minerals are copper, iron, and zinc, among others.
